question from K&B - pl clarify

This is the question from K&B of chapter 3. ------------------- class CardBoard { Short story = 5; CardBoard go(CardBoard cb) { cb = null; return cb; } public static void main(String[] args) { CardBoard c1 = new CardBoard(); CardBoard c2 = new CardBoard(); CardBoard c3 = c1.go(c2); c1 = null; // do Stuff } } When // doStuff is reached, how many objects are eligible for GC? --------- My thinking was the objects associated to c1 and c3 are eligible. Considering the Short wrapper object associated with each of them, there should be 4 objects eligible for GB. Obviously, the answer is wrong. Can you explain whats wrong in my understanding please?